When I first got into racing drones, I opted to use a BIC cigarette lighter to shrink my heatshrink when doing my builds. For small-diameter, black heat shrinks, this tactic is low cost and works well. As I got more invested into building drones that not only worked, but looked good – I decided I needed to upgrade my toolkit to include a heat gun. I’m glad I did!
I’ve since discovered that a good heat gun is useful for more than just heat shrink. It can be used in all manner of things from plastic carving to fixing PCBs. In this article, I’ll outline some of the interesting things you can do with heat guns and make some recommendations on how you can get one of your own.
Using a Heat Gun
Heat guns operate much like soldering irons, so most will have a simple on-off switch and a temperature knob as the only controls. Like a soldering iron, you’ll rarely need to use anything less than full temperature unless you are doing PCB work.
One thing I learned early on is that a good heat gun should not be treated like a hair drier. The air that comes out of these devices is extraordinarily hot. Even brief contact with the air stream of a heat gun at full blast can cause a 2nd degree burn. If you want to gauge the heat of your gun, do not use your hand! Point it at some wood or plastic and watch how quickly it melts.
Most heat guns will come with an assortment of nozzles. These can be used to shape the hot air coming out of the gun. Larger tips can be used to spread the thermal load and are useful for shrinking heat shrink. Smaller tips can be used to concentrate the heat stream into a finer point and can be to melt solder, heat metal parts up and cut through plastics and foam.
As mentioned above, heat guns have several practical uses. In general, if you need to heat something up, a heat gun is a good bet for doing it. Here are some mini-quad related uses I have found thus far:
Shrinking Heat Shrink
OK – this one’s a little obvious. It’s likely the reason why you would be looking into buying a heat gun. Here’s the thing though – until you own a nice heat gun you cannot know how much easier it makes the heat shrinking process. Not only does it significantly clean up the shrinking process (over using a lighter or soldering iron, for instance) – it is also much easier to apply the heat thanks to exchangeable nozzles.
If you are simply shrinking 1/8″ or smaller diameter black heat shrink, you probably do not need a heat gun. However, if you ever want to shrink colored or clear heat shrink or want to shrink large-diameter heat shrink, a heat gun is a requirement.
Plastic / 3D Print Finishing
Careful application of a heat gun can be used to repair surface defects and blemishes on most plastics. The idea is you heat up the defective plastic then use a hard, flat surface to clean it up. This technique can be used in lieu of sanding to clear up the ridges that form from 3D printing, creating a professional-looking product. Just be careful when doing this the first few times – heat guns can easily melt holes in plastic and even burn it. Start with a light application of heat by using a wider nozzle or a lower temperature setting before moving up to hotter settings.
Desoldering SMD Parts
Ever needed to remove a pin header or mis-placed connector? Or perhaps you wanted to remove a SMD chip, LED, capacitors, etc. for some reason? Heat guns are the industry standard way to do this. Using a small nozzle, apply heat in a circular motion to the soldered pins while gently pulling the component off of the PCB with some tweezers. Once the solder holding the component to the PCB melts, it will pop free. Just be careful not to damage the PCB or the component by using excessive heat. We recommend you practice the technique on some spare parts you don’t care about before diving in on something you don’t want to ruin.
Hot Glue Shaping
Similar to re-finishing plastic, a heat gun can be used to soften hot glue blobs so that you can shape them with your fingers to be more aesthetically pleasing. Using this technique, you can actually make some pretty interesting shapes with hot glue. For example, I was able to add some reinforcement to the lobes of a CP antenna using hot glue that ended up looking pretty good.
While on the subject of hot glue, a heat gun can be used to easily melt hot glue so it stops bonding two parts together. This can be really useful when the parts are pressed together firmly or when a thick layer of hot glue is used – situations where it is nearly impossible to remove the hot glue using just the hot glue gun.
Sometimes metal components are press-fit together using differential heating. This basically “shrinks” one part around another, providing an extremely strong friction bond. One place this is commonly used in miniquads is with brushless motor bearings.
Heat guns can be used to direct a large amount of heat at specific metal components to allow you to remove press-fit components or do your own press-fitting. As mentioned above, this is specifically useful when replacing motor bearings.
Sometimes the pins of chips on a flight controller, ESC or RC RX can come unseated. This can be caused by a particularly violent crash or improper manufacturing standards. What is actually happening is the solder that holds these pins to the PCB is cracking. This manifests as flight controllers that suddenly lose a feature or have a feature that intermittently stops working while in flight.
If you can figure out which chip is causing the problem, you can fix it with a hot air gun. To do this, apply hot air to the pins of the chip in a circular motion until the solder melts, or “reflows”. This will re-connect the pin to the PCB and fix your component. Many electrical gremlins can be fixed in this way. I do want to mention that this procedure is not for the faint of heart and that you can easily damage your electronics by applying too much heat – I highly recommend you practice on some scrap PCBs before doing anything with your working components.
This process can also be used to actually build SMD boards from scratch or wholesale replace chips and other components on your board. This is a much more complicated topic, though, and is past my current skill level. I will drop this video in case you are interested in learning:
One of the best ways to cut nice clean holes in plastics is to use a heated hobby knife. The heated tip will clean up the burrs that normally form during this process and make cutting the plastic much easier. You can see me using this technique to modify my FatShark goggles to install a La Forge module in our video from last year:
In the above video, I used a cigarette lighter to heat the blade. Unsurprisingly, a heat gun is a far superior way to accomplish this same technique. It reduces carbon build up on the knife, causing it to last longer and can also heat the knife up far hotter and quicker.
Choosing a Heat Gun
When purchasing a heat gun, you can expect to spend at least $15. As you might expect, professional heat guns can cost several hundred dollars. What is the difference and what features should you look for? Let’s discuss:
Form Factor – There are two major styles of heat guns on the market. Some are L-shaped like electric drills, while others are pen-shaped like dremels. We prefer the pen-shaped devices as it allows you more control with your heat.
- Heating Speed – A nice heat gun will be able to heat up rapidly. Nothing is worse than waiting for a minute or longer just to do some heat shrinking.
- Power – This matters less than you might think for our purposes. Power is great for drying hair or heating large areas, but our use for a heat gun generally consists of heating something really small really hot. Anything rated at over 100W should be sufficient.
- Removable tips – More advanced heat guns will come with removable tips. They will often ship with multiple different types of tips which should allow you to more precisely do heat shrinking, solder reworks, etc.
- Adjustable Heat – Being able to control the heat coming out of your gun is pretty important for solder reworking but doesn’t matter so much for other heat gun uses.
- Tip Protection – Some heat guns come with a protective shroud that protects you from accidentally touching the hot metal nozzle. These nozzles will instantly roast your skin, just like a soldering iron, so some protection is handy.
- Automatic Shutoff – A heat gun left on and placed on a workbench can quickly cause a fire. Most nicer heat guns have docks that you can place them in which cause them to automatically shut off – a nice safety feature.
- Durability and Warranty – This is where a lot of the money for expensive heat guns goes. If you buy a nice Weller for $500+, you’re buying a warranty that that gun will work for a long time, even if you use it professionally, 24/7. For hobbyist use, cheap Chinese-made heat guns will perform comparably, but don’t be surprised if they don’t last a super long time.
Heat Gun Suggestions
Here are a few heat guns on the market we have some experience with:
Heaterizer XL-3000 300W Portable Gun
This is a really nice, in-expensive heat gun. It’s a generic Chinese product so you can find it with various different labels all over the market. At less than $15 it’s pretty bare bones, but it heats up very fast and makes short work of heat shrink. We also like the protective shroud around the nozzle.
Zeny 858D Hot Air Gun
If you’re looking for a heat gun that can potential do solder rework, you’ll probably want to grab the Zeny 858D or a similar heat gun. This gun has adjustable temperature controls, heats rapidly, has removable tips and an automatic shut-off feature.
Zeny 862D Soldering Iron + Hot Air Combo
I bought one of these last year when my last soldering iron died and quickly fell in love with it. The hot air gun that comes with this kit is extremely effective. It heats up rapidly, has a controllable temperature, removable tips and an automatic shut-off when you place the heat gun in it’s dock. I highly recommend this to anyone looking for a soldering iron and a hot air gun.